code: def fetch_extension(self) -> str:
      val = self._backend.get_file_attribute(
          self._container_id, self._container_type, self._path
      )
      return val.ext
  
file_path: neptune-client/src/neptune/attributes/atoms/file.py
imports: from typing import Optional
  from neptune.attributes.atoms.atom import Atom
  from neptune.internal.operation import UploadFile
  from neptune.internal.utils import verify_type
  from neptune.types.atoms.file import File
label_desc: Use image node_id 4 for calling the File obj's underlying member method code with example usage: obj.fetch_extension() and returns: val